In the manufacture of many different textile products, it is desirable to be able to produce yarns having a great deal of diversity. It is also desirable to be able to utilize yarns that have the least cost possible while still having desirable aesthetic and other properties to produce fabrics having good hand and appearance.
In the past there have been a number of different attempts to produce yarns composed of more than one different fiber so that the yarn will have a distinctive appearance, such as provided by U.S. Pat. No. 4,383,403. Additionally, there have been attempts to produce multiple layered spun yarns having different properties between a core and a sheath so that desirable properties of two different types of fibers may be utilized to produce a composite spun yarn having most of the desirable properties of both. One such procedure is shown in Japanese patent publication No. 11775, and is commonly referred to as the Palpa process. While the yarns produced by the process do have a number of significant advantages, they sometimes tend to be more uneven than desired so that there is not complete uniformity of coverage of the core fibers by the sheath fibers.
According to the present invention, an advantageous spun yarn is produced that has a uniform core and sheath construction, the sheath surrounding the core. The yarn is formed from two different fibers, which fibers have distinctly different properties, and the yarn produced according to the invention has very desirable evenness of coverage, and is extremely versatile, being utilizable to produce yarns, and resulting fabrics, having distinctive appearances, as well as having most of the desirable properties from both of the fibers.
According to one aspect of the present invention, a method is provided for producing a roving having a first fiber substantially covering a second fiber. The roving is produced by the following steps: (a) A sliver of first fibers and a sliver of second fibers, which have clearly distinctive properties from the first fibers, are fed in generally parallel paths. (b) The slivers are continously drafted to produce two drafted slivers. (c) The path of at least one of the drafted slivers is changed so that the drafted slivers proceed in intersecting paths, and at substantially the same speed. Preferably the second drafted sliver moves in a continuous straight line, while the path of the first drafted sliver is diverted to intersect the path of the second sliver. (d) The fibers of the first drafted sliver are caused to wrap around the fibers of the second drafted sliver, with an angle of intersection between the two paths of slivers in the range of 60.degree.-120.degree. (preferably about 90.degree.) to produce a composite drafted sliver-roving. And, (e) the composite sliver-roving is twisted (e.g. by a mechanical roving flyer frame) into a roving having the majority of the second fibers in a core, and the majority of the first fibers in a sheath surrounding the core.
The invention also comprises a method of producing a spun yarn from the roving set forth above, by spinning (e.g. mechanically spinning on a spinning frame) the composite roving to produce a spun yarn with the sheath and core. In the final yarn produced, about 75-90 percent of the second fibers are in the core and about 25-10 percent in the sheath, while substantially 100 percent of the first fibers are in the sheath.
The yarn produced according to the invention has numerous potential desirable characteristics, and the method is versatile so as to produce a wide variety of different yarns. For example, by putting a less expensive fiber in the center and a more expensive or desirable fiber on the outside for better aesthetics and fabric performance, desirable yarns (and resulting fabrics) can be produced less expensively. For instance, the yarn according to the present invention may have a core of polyester, and a sheath of wool, the percentage of polyester to wool in the final yarn being about 40-60 percent/60-40 percent. Alternatively, a yarn can be produced that has a high strength fiber as the core and a more luxurious fiber on the outside, and/or the yarn can be produced wherein the different fibers have distinctly different colors and/or dyeability properties, resulting in a very distinctive looking yarn and resulting fabric.
It is the primary object of the present invention to provide a method and apparatus of producing, and to produce, a yarn with a core and a sheath and composed of different fibers having distinctly different characteristics. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.